An example of a congestion control method when the radio base station of a mobile communication system is congested, is the method disclosed in JP-A-No. 6-105360. According to this, a base station control device detects congestion of a radio base station, and transmits a congestion notification signal to a remote maintenance device. The remote maintenance device transmits a restriction information signal to a base station control device considering the strengthening/mitigation of the restriction level. The restriction information signal contains an identification code of the radio base station which is the restriction target, eight restriction patterns of one octet which, when mobile terminals are divided into groups, express whether or not each group is a restriction target by one bit respectively, and a change cycle which indicates the application time of one restriction pattern. The base station control device, when the restriction information signal is received, transmits one restriction pattern to the radio base station during congestion. Based on the change cycle, the remaining seven restriction patterns are transmitted one by one, and the terminal group of the restriction target is changed over. The radio base station, when a restriction pattern is received, restricts the registration messages and call connections received from a specific terminal group by reporting which terminal group is under restriction to the mobile terminals under it.
When a terminal transmits a call control message (a registration message/call setup message) to the radio base station, the radio base station can interpret these layer 3 messages, and restrict transmission of new calls alone. Likewise, when a mobile switching center and the base station control device transmit a call control message, the radio base station can interpret layer 3 messages, and restrict incoming calls receipt.
An example of a receive restriction on incoming calls method when the radio base station is congested is the method disclosed in JP-A No. 10-336321. According to this, a maintenance operator supervises congestion of the base station by measuring, at a mobile switching center, the number of call setup connection failure messages transmitted to the mobile switching center when the radio base station fails to make a call connection due to the fact that all channels of the base station are in use. If the maintenance operator determines that a receive restriction on incoming calls for the base station is required, the identification number of the restriction target base station and restriction rate are registered in a restriction registration table of the mobile switching center with a maintenance command. When the mobile switching center receives an incoming call, the base station which accommodates a called receiving partner mobile station is specified by looking up a terminal location position management database, and it is determined whether the base station is a restriction target on the restriction registration table is referred to before paging the mobile station making a call.
If the base station is the restriction target, the mobile switching center cancels stops the call according to the restriction rate.